Spoke for a bicycle wheel, bicycle wheel comprising such a spoke and method for manufacturing such a spoke

ABSTRACT

A spoke for a bicycle wheel has an elongated metallic material body that extends along a longitudinal axis X-X and has a first end portion for the attachment to a hub of a bicycle wheel, a second end portion for the attachment to a rim of a bicycle wheel and an intermediate portion having a portion which is flattened in a transversal direction Z perpendicular to the longitudinal axis X-X and extending along the longitudinal axis X-X up to the first end portion. The first end portion of the spoke is also flattened in the transversal direction Z and is gradually joined to the flattened portion of the intermediate portion along the longitudinal axis X-X.

FIELD OF INVENTION

The present invention relates to a spoke for a bicycle wheel. Morespecifically, the invention relates to a spoke for a bicycle wheel madeof metallic material, a bicycle wheel comprising a plurality of suchspokes, and a method for manufacturing such a spoke.

BACKGROUND

As known, the spokes for a bicycle wheel consist of substantiallywire-shaped elements, generally made of metal like steel or aluminum oralloys thereof, provided with a first end portion for the attachment tothe central part of the wheel consisting of the hub and a second endportion for the attachment to the rim on which the tire is mounted.Typically, the end portion for attachment to the hub is shaped so as todefine a widened head intended to be stably housed in suitable seatsformed in the hub. The end portion for attachment to the rim has athreaded zone to allow fastening to the rim and adjustment of thetension of the spoke using a suitable nut or nipple.

In order to enhance the aesthetics and the aerodynamic characteristicsof the wheels, flattened spokes have been proposed, i.e. spokes in whichthe body portion between the two end portions for the attachment to thehub and to the rim is flattened.

SUMMARY

The object of the present invention is that of providing a flattenedmetal spoke which, as well as aesthetically distinguishing itself fromthose of the prior art, is suitable for being connected to the hub atthe front surface thereof (thus simplifying the manufacturing of thehub), without, at the same time, having the drawbacks of the flattenedspokes of the prior art made of metallic material.

The present invention, therefore, relates, in a first aspect thereof, toa spoke for a bicycle wheel, comprising an elongated body made ofmetallic material extending along a longitudinal axis X-X and having:

-   -   a first end portion for attachment to a hub of a bicycle wheel;    -   a second end portion for attachment to a rim of a bicycle wheel;    -   an intermediate portion between said first and second end        portions, in which said intermediate portion comprises a portion        which is flattened in a transversal direction Z perpendicular to        said longitudinal axis X-X and extending along said longitudinal        axis X-X up to said first end portion;

wherein said first end portion is flattened in said transversaldirection Z and is gradually joined to said flattened portion of saidintermediate portion along said longitudinal axis X-X.

BRIEF DESCRIPTION OF THE DRAWING(S)

Further characteristics and advantages of the present invention shallbecome clearer from the following detailed description of a preferredembodiment thereof, given with reference to the attached drawings. Insuch drawings,

FIG. 1 is an enlarged schematic front view of a spoke for a bicyclewheel according to the present invention;

FIG. 2 is a schematic side view of the spoke of FIG. 1;

FIG. 3 is an enlarged schematic perspective view of an end portion ofthe spoke of FIG. 1;

FIGS. 4 a-4 d represent different cross sections of the spoke of FIG. 1taken at the different section lines shown in FIG. 1, for each sectionthe equivalent circle also being represented, the area of which is equalto the area of the section in question;

FIG. 5 is a schematic perspective view, from a first point of view, of acentral portion of the wheel of the present invention in a firstembodiment thereof;

FIG. 6 is an enlarged schematic section view of a portion of hub of thewheel of the present invention;

FIG. 7 is a schematic perspective view of a central portion of the wheelof the present invention in a second embodiment thereof.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) Introduction to theEmbodiments

Carbon-reinforced flattened spokes are advantageous because they arelightweight. The use of such a material, however, requires the need tomake the spoke in two distinct elements: a first elongated and flattenedcarbon fiber element in which the head for the attachment to the hub isdefined, and a second metallic connection element hinged to a free endof the carbon fiber element and provided with a threading to allow theattachment to the rim and the tensioning of the spoke.

The Applicant has noted that prior art spokes discussed above have somedrawbacks. In particular, the need to manufacture the spoke in twodistinct elements is technically complicated, and consequently involveshigh production costs. Further, due to the necessary size of the spokeat the hub, spokes made of uniform thickness are heavy along theirentire length, even though certain portions of the spoke do not requirea uniform thickness.

This means, as well as inevitable technical complications in themanufacturing of the head for the attachment to the hub, that a heavyspoke is obtained, due to the substantial size of the head for theattachment to the hub. Moreover, the substantial change in section atthe passage zone between the intermediate portion of the spoke and thehead for the attachment to the hub defines a critically important zonewith a high concentration of tension at the passage zone, due to 1) thetransmission of the driving torque between hub and spoke, and 2) becausein such a zone the same traction stresses are amplified by local effectslinked to the attachment to the hub.

The Applicant has therefore focused above all upon the design andmanufacture of a flattened spoke made of metal material (flattened metalspokes being generally known), so as to be able to make the spoke in asingle body.

Throughout the present description and the subsequent claims, theexpression “flattened portion”, used with reference to the intermediateportion or to the first end portion of the spoke of the presentinvention, is used to indicate a portion that has been squashed alongthe transversal direction Z so that the cross section of such a portionhas one dimension (typically defining the thickness of the spoke portionin question) substantially smaller than the other dimension (typicallydefining the width of the spoke portion in question). For example, aspoke portion is flattened when the thickness (or generically adimension of the cross section) of the spoke portion in question is lessthan 1.5 times the width (or generically the other dimension of thecross section) of the spoke portion in question. Therefore, the oppositefaces of said spoke portion do not necessarily have to be perfectly flatand parallel; i.e. it is also possible for such faces to have asubstantially elliptical progression or a substantially circularprogression with a wide radius of curvature.

Advantageously, the spoke of the present invention, as well as havingaerodynamic characteristics and pleasant aesthetics typical of flattenedspokes, also has a body that is flattened both at the intermediateportion of the elongated element constituting the body of the spoke andat the first end portion constituting the head for the attachment to thehub, with the latter gradually joined to the flattened intermediateportion of the spoke. Such a spoke therefore has an aesthetic look whichis different from that of the metallic spokes disclosed in the patentsof the prior art. Moreover, the spoke of the present invention isparticularly suitable for being associated with the hub at the frontsurface thereof; indeed, the provision of a head for the attachment tothe hub that is flattened in the transversal direction Z ensures astable housing of such a head in the hub. Even more advantageously, theflattened head, as well as contributing to the manufacturing of a spokehaving a lower overall weight with respect to those of the prior art,prevents the rotation of the spoke about its longitudinal axis duringtensioning. The spoke of the invention also has characteristics ofresistance to the transfer of the driving torque exerted by the hubbetter than those spokes discussed above; this is due to the fact thatit has a head for the attachment to the hub that is flattened andgradually joined to the flattened intermediate portion of the spoke.

Throughout the present description and the subsequent claims, the term“profile”, used with reference to the cross section of any portion ofthe spoke of the present invention, is used to indicate the shapedefined by the outline of such a cross section. The expression“substantially the same profile”, used with reference to the sections ofthe spoke of the present invention, is thus used to indicate that suchsections have a substantially identical shape, and not necessarily alsoa substantially identical area. The expression “substantially the same”,used with reference to the profiles of the sections of the spoke of thepresent invention, also embraces the possibility of small differences inthe profiles, for example due to joins, or bevels or tapers. Further,for example, in the context of this application, a rectangular profileis substantially the same as the profile shown in FIGS. 4 a through 4 ewith opposite faces that are rounded (not necessarily flat) and/orgradually joined at their corners although in alternate embodiments, theprofile could include sharp corners.

Description of the Embodiments

In the attached Figures, a spoke for bicycle wheels is indicated withreference numeral 10. The spoke 10 comprises an elongated body 20 ofmetallic material like steel or aluminum or alloys thereof (preferablyaluminum alloy) extending along a longitudinal axis X-X. Such a type ofspoke is intended to be used in a bicycle wheel to connect a hub 100(illustrated in Figures from 5 to 7) to a rim (not illustrated).

The body 20 of the spoke 10 comprises a first end portion 30 defining ahead for the attachment to the hub, a second threaded end portion 40defining a zone for the attachment to the rim and an intermediateportion 50. Such an intermediate portion 50 in turn comprises a portion60 which is flattened in a transversal direction Z perpendicular to thelongitudinal axis X-X of the spoke 10 and extending along saidlongitudinal axis X-X up to the head 30 for the attachment to the hub;on the opposite side, the intermediate portion 50 comprises acylindrical portion 70 extending along the longitudinal axis X-X up tothe head 40 for the attachment to the rim.

The head 30 for the attachment to the hub is also flattened in thetransversal direction Z and is gradually joined, along the longitudinalaxis X-X of the intermediate portion 50, to the flattened portion 60 ofthe elongated body 20 through a joining zone 65 (visible in detail inFIG. 3).

As better illustrated in FIGS. 4 a-4 e, the elongated body 20 has, alongthe longitudinal axis X-X, cross sections having substantially the sameprofiles (or else shapes), i.e. sections all being substantiallyrectangular, elliptical or circular in shape with a wide radium ofcurvature, with squashed—not necessarily flat—and/or gradually joinedopposite faces. The broken line in FIGS. 4 a-4 e indicates the circlethat defines an equivalent area of the spoke with the flattened profile.The equivalent area represents, for each section, the area of ahypothetical non-flattened cylindrical wire which has, in each section,the same area as the spoke with a flattened profile. In particular, thehead 30 for the attachment to the hub has a cross section havingsubstantially the same profile as the cross section of the flattenedportion 60 of the intermediate portion 50 of the elongated body 20 at azone 80 thereof adjacent to the head 30 for the attachment to the hub(FIGS. 4 a and 4 b).

Advantageously, a gradual passage from the flattened intermediateportion of the spoke to the head for the attachment to the hub isobtained.

While having substantially the same profiles, the cross sections of theflattened portion 60 of the intermediate portion 50 of the elongatedbody 20 have a different area, starting from the section A-A at the head30 for the attachment to the hub up to near the section N-N close to thecylindrical portion 70 adjacent to the head 40 for the attachment to therim. In particular, the flattened portion 60 of the intermediate portion50 of the elongated body 20 has, along the longitudinal axis X-X, crosssections of increasing area towards the zone 80 adjacent to the head 30for the attachment to the hub and towards the cylindrical portion 70adjacent to the head 40 for the attachment to the rim. The spoke of theinvention thus has a small amount of material (less cross-sectionalarea) in its central zone, whereas it is more solid (greatercross-sectional area) near to the heads for the attachment to the huband to the rim, while still keeping, along the entire length for whichit extends, substantially the same profile of the cross sections. Thisadvantageously allows the overall weight of the spoke of the presentinvention to be reduced with respect to known spokes having crosssections of constant area for the entire length on which they extend.

In different embodiments, the flattened portion 60 of said intermediateportion 50 may have, along its longitudinal axis X-X, cross sections ofdifferent area.

As best seen in FIG. 3, the head 30 for the attachment to the hubcomprises a pair of opposite front surfaces 31, 32, respectively frontand rear, that are substantially flat; such surfaces 31 and 32 extendalong the longitudinal axis X-X of the spoke for a portion of lengththat is greater than the dimension of the head 30 in the transversaldirection Z. One of the front surfaces 31, 32, in the attached Figuresthe surface 32, defines a front abutment surface of the head 30 on thehub 100 of the bicycle wheel when the spoke 10 is mounted on the hub, asshall be better described hereafter with reference to FIGS. 5-7. Thesurfaces 31 and 32 are slightly flared outwards, so that the head 30 is,in the transversal direction Z, greater in thickness than the thicknessof the flattened portion 60. Such surfaces could also be substantiallystraight or narrow inwards, so that the head 30 has substantially thesame (FIG. 4 a-1) or smaller thickness FIG. 4 a-2) with respect to thethickness of the flattened portion 60.

The head 30 for the attachment to the hub also comprises, along thelongitudinal axis X-X, a pair of substantially cylindrical side surfaceportions 33, 34 arranged symmetrically with respect to the longitudinalaxis X-X; each of such opposite surfaces defines a side and axialabutment surface of the head 30 on the hub 100 of the bicycle wheel whenthe spoke 10 is mounted on the hub, as shall be better describedhereafter with reference to FIGS. 5-7.

The hub 100 comprises a plurality of seats 110 formed on a front annularsurface 120 thereof; each of the seats 110 is intended to receive thehead 30 of a respective spoke 10 when it is mounted on the hub. Inparticular, each seat 110 comprises a substantially flat front surface111. When the spoke 10 is mounted on the hub 100, the head 30 is housedin the seat 110 arranging the front surface 32 of the head 30 inabutment against the front surface 111 of the seat 110, as shown inFIGS. 5-7.

Advantageously, the provision of the substantially flat front surface 32and the substantially flat front surface 111 provided in the hub, makeseasier the assembly and the tensioning of the spoke of the presentinvention, preventing it from rotating about its axis, and contributesto achieving a stable connection of the spoke on the hub, avoiding thatpossible torsions of the spoke caused by collisions or vibrations couldalter the desired characteristics of aerodynamics and aesthetics

Each seat 110 also comprises a pair of side surface portions 112, 113 ofa shape matching the side surface portions 33, 34 of the head 30 (FIG.7); these portions, when the spoke 10 is mounted on the hub, arearranged in abutment against the side surfaces 112, 113 of the seat 110,as shown in FIGS. 5-7.

The provision in the spoke of the invention of substantially cylindricalportions for side surfaces portions 33, 34, and the corresponding sidesurface portions 112, 113 of matching shape provided in the hub, allowsthe self-alignment of the spoke during its assembly onto the rim, thanksto the small adjustment movements that are allowed by the relativesliding of the matching surfaces defined above.

The seats 110 also comprise a seat portion 115 intended to receive thebody portion 20 immediately adjacent to the head 30.

In the embodiment of the wheel of the present invention illustrated inFIGS. 5 and 6, the seats 110 of the hub 100 are orientated according toan orientation substantially tangential to the front annular surface 120of the hub; in particular, the seats 110 are alternatively formed on twodifferent planes of said front surface 120 and orientated substantiallytangentially in the opposite direction so as to achieve a wheelconfiguration with crossed spokes. In such an embodiment, the movementof the spokes in the direction of the axis of the hub outwards isprevented preferably by associating an annular counter element 117(shown removed) with the hub at the front surface 120 of the hub, such acounter element 117 being suitable for operating in abutment against thespokes 10 at the zone in which they cross over.

In the embodiment of the wheel of the present invention illustrated inFIG. 7, the seats 100, and consequently the spokes 10, are orientatedalong a substantially radial orientation. Also in such an embodiment,the movement of the spokes in the direction of the axis of the huboutwards is prevented by associating an annular counter element 130 withthe hub at the front surface 120 of the hub, such an element beingsuitable for operating in abutment against the front surfaces 31 of theheads 30 of the spokes 10.

The manufacturing of the spoke 10 of the present invention can becarried out starting from a wire of metallic material in an annealedstate having a cross section of area equal to the area of the crosssection of the desired head for attachment to the hub or from a wire ofmetallic material in an annealed state having a cross section of smallerarea than the area of the cross section of the desired head forattachment to the hub, and in particular with a diameter equal to orsmaller than that of the section of the desired head for attachment tothe rim.

In the case in which the area of the starting section of the wire ofmetallic material is equal to that of the section of the desired headfor attachment to the hub, one proceeds by firstly cutting a filament ofpredetermined length having a circular section from such a startingwire. Then the filament is shaped through plastic deformation, cold orhot (for example through hammering), to obtain cross sections (generallycircular) of different areas between the head for attachment to the huband the head for attachment to the rim. Optionally, an intermediateannealing heat treatment can be carried out to promote the reduction inhardness of the material and to increase its deformability.

One then proceeds with a step of pressing or squashing the filament bycold or hot plastic deformation in the various zones along thelongitudinal axis of the filament to obtain the desired squashedprofile. Such a squashing step can for example carried out by molding(using a suitably shaped mold and countermold) or by rolling (passingthe filament through a pair of suitably shaped rollers). Also in thiscase, optionally, an intermediate annealing heat treatment can becarried out to promote the reduction in hardness of the material and toincrease its deformability.

One then proceeds with the shaping of the head for attachment to thehub. Such a step comprises a squashing by molding of the head forattachment to the hub and can be carried out at the same time as thesquashing step of the filament mentioned above.

Then the calibration of the length of the spoke is carried out throughtrimming or butting of the head for attachment to the hub.

The filament is then subjected to a drawing temper heat treatment toimprove its mechanical characteristics.

One then proceeds with the threading of the head for attachment to therim. Such a threading can be carried out by rolling or by chip-removalmachining. In the case of threading by rolling, the operation requiresthat the profile of the thread is obtained by plastic deformationstarting from a filament with a pre-processing diameter smaller than thediameter of the head for attachment to the rim. In the case of threadingby shaving-removal, the operation requires that the profile of thethread is obtained by removal of material from a filament with apre-processing diameter equal to (or possibly greater than) that of thehead for attachment to the rim.

Finally, a surface protection treatment on the spoke or a portionthereof is carried out by anodization or by painting.

On the other hand, in the case in which the area of the starting sectionof the wire of metallic material is smaller than that of the section ofthe desired head for attachment to the hub, one proceeds by firstlycutting a filament of predetermined length having a circular sectionfrom a starting wire having a diameter equal to or greater than that ofthe desired head for attachment to the rim. The steps of the method formanufacturing the spoke are totally identical to those described above,with the sole difference that the shaping of the head for attachment tothe hub is carried out in this case by upsetting; in particular, duringsuch a step the section of the head is progressively increased throughaxial movement of the material until the desired section is obtained.

The manufacturing methods described above advantageously allow a spoketo be obtained having sections of different area along its length. Inparticular, such methods allow a spoke to be obtained with a smallamount of material in its central zone, where the traction stresses arenot amplified by local effects related to the attachment to the huband/or to the rim. This advantageously allows the overall weight of thespoke of the present invention to be reduced with respect to knownspokes, having cross sections of constant area for the entire length onwhich they extend.

1. A spoke for a bicycle wheel, comprising an elongated body of metallicmaterial extending along a longitudinal axis X-X comprising: a first endportion for the attachment to a hub of a bicycle wheel; a second endportion for the attachment to a rim of a bicycle wheel; an intermediateportion between said first and second end portions, in which saidintermediate portion comprises a flattened portion that is flattened ina transversal direction Z perpendicular to said longitudinal axis X-Xand extending along said longitudinal axis X-X up to said first endportion; wherein said first end portion is flattened in said transversaldirection Z and is gradually joined to said flattened portion along saidlongitudinal axis X-X; wherein said first end portion comprises, alongsaid longitudinal axis X-X, a pair of substantially cylindrical oppositeside surface portions defining side and axial abutment surfaces of saidfirst end portion configured to engage a hub of a bicycle wheel.
 2. Thespoke of claim 1 wherein a thickness of said first end portion isgreater than a thickness of said flattened portion in said transversaldirection Z.
 3. The spoke of claim 1 wherein the thickness of said firstend portion is substantially the same as the thickness of said flattenedportion in said transversal direction Z.
 4. The spoke of claim 1 whereinthe thickness of said first end portion is smaller than the thickness ofsaid flattened portion in said transversal direction Z.
 5. The spoke ofclaim 1 wherein said flattened portion comprises a zone adjacent to saidfirst end portion and wherein said first end portion has a cross sectionhaving a profile that is substantially the same shape as the profile ofthe cross section of said zone adjacent to said first end portion. 6.The spoke of claim 1 wherein said second end portion is threaded andwherein said intermediate portion comprises a cylindrical portionextending along said longitudinal axis X-X and adjacent to said secondend portion.
 7. The spoke of claim 1 wherein said flattened portion ofsaid intermediate portion has, along said longitudinal axis X-X, aplurality of cross sections of different area.
 8. The spoke of claim 7wherein said flattened portion has, from a midpoint thereof along saidlongitudinal axis X-X, cross sections of increasing area towards saidzone adjacent to said first end portion and towards the cylindricalportion adjacent to said second end portion.
 9. The spoke of claim 1wherein said first end portion comprises at least one substantially flatfront surface extending along said longitudinal axis X-X and defining afront abutment surface of said first end portion configured to engage ahub of a bicycle wheel.
 10. The spoke of claim 9 wherein said at leastone front surface extends along said longitudinal axis X-X for a lengthportion greater than the dimension of said first end portion in saidtransversal direction Z.
 11. A bicycle wheel, comprising: a hub; a rim;and a plurality of spokes extending between said hub and said rim;wherein said plurality of spokes are of the type claimed in claim
 1. 12.The bicycle wheel of claim 11 wherein said hub comprises a front annularsurface on which a plurality of seats are formed for housing said firstend portions of said spokes.
 13. The bicycle wheel of claim 12 whereineach of said first end portions of spoke comprises at least one firstsubstantially flat front surface extending along said longitudinal axisX-X and operating in abutment against a corresponding substantially flatfront surface of a respective seat formed in the hub.
 14. The bicyclewheel of claim 11 wherein each of said first end portions of spokecomprises a pair of substantially cylindrical opposite side surfaceportions which operate in abutment against corresponding opposite sidesurface portions of a respective seat formed in the hub, wherein saidside surfaces of each of said seats have a shape corresponding to thatof said side surfaces of said first end portions of spoke.
 15. Thebicycle wheel of claim 11 wherein said seats are formed on said frontsurface of the hub and have a substantially tangential orientation tosaid hub.
 16. The bicycle wheel of claim 11 wherein said seats areformed on said front surface of the hub and have a substantially radialorientation to said hub.
 17. A bicycle wheel spoke comprising: a firstflattened end portion configured for attachment to a hub of a bicyclewheel; a second end portion configured for attachment to a rim of abicycle wheel; an intermediate portion between said first and second endportions, in which said intermediate portion comprises a flattenedportion; wherein said first end portion comprises a pair ofsubstantially cylindrical opposite side surface portions defining sideand axial abutment surfaces of said first end portion configured toengage a hub of a bicycle wheel.
 18. The spoke of claim 17 wherein thecross sectional area of said first end portion is greater than the crosssectional area of said flattened portion.
 19. The spoke of claim 17wherein said flattened portion comprises a zone adjacent to said firstend portion and wherein said first end portion has a cross sectionhaving a profile that is substantially the same shape as the profile ofthe cross section of said zone adjacent to said first end portion. 20.The spoke of claim 17 wherein said second end portion is threaded andwherein said intermediate portion comprises a cylindrical portion. 21.The spoke of claim 17 wherein said flattened portion of saidintermediate portion has a plurality of cross sections of differentarea.
 22. The spoke of claim 21 wherein said flattened portion has, froma midpoint thereof, cross sections of increasing area towards said zoneadjacent to said first end portion and towards a cylindrical portionadjacent to said second end portion.
 23. The spoke of claim 17 whereinsaid first end portion comprises at least one substantially flat frontsurface defining at least one front abutment surface of said first endportion configured to engage a hub of a bicycle wheel.
 24. The spoke ofclaim 23 wherein said at least one front abutment surface extends alonga longitudinal axis X-X for a length greater than the dimension of saidfirst end portion in a transversal direction Z.
 25. The spoke of claim17 wherein the first end portion and the intermediate portion havesubstantially the same cross sectional shape.
 26. A spoke for a bicyclewheel, comprising an elongated body of metallic material extending alonga longitudinal axis X-X comprising: a first end portion for theattachment to a hub of a bicycle wheel; a second end portion for theattachment to a rim of a bicycle wheel; and an intermediate portionbetween said first and second end portions, in which said intermediateportion comprises a flattened portion that is flattened in a transversaldirection Z perpendicular to said longitudinal axis X-X and extendingalong said longitudinal axis X-X up to said first end portion; whereinsaid first end portion is flattened in said transversal direction Z andis gradually joined to said flattened portion along said longitudinalaxis X-X; and wherein said second end portion is threaded and whereinsaid intermediate portion comprises a cylindrical portion extendingalong said longitudinal axis X-X and adjacent to said second endportion.